The present invention relates to antibodies, compositions and methods for diagnosing and treating inflammation. More particularly, the present invention relates to the use of anti scavenger receptor antibodies in treatment of an inflammatory response.
Inflammation is a physiological condition characterized in the acute form by the classical signs of pain, heat, redness, swelling and loss of function. Inflammation often accompanies diseases such as Multiple Sclerosis (MS), osteoarthritis, Inflammatory Bowl Disease (IBD) including Crohn's disease and ulcerative colitis, Rheumatoid Arthritis (RA), SLE, type I diabetes (IDDM), atherosclerosis, encephalomyelitis, Alzheimer's disease, stroke, traumatic brain injury, Parkinson's disease, septic shock and others. In most cases, there is no effective cure for inflammation associated with such disease and existing treatments are palliative and largely fail to control the underlying causes of tissue degradation.
Scavenger receptors (SRs) are cell surface proteins, which are typically found on macrophages and bind various types of chemically modified lipoproteins (1-3), such as low-density lipoprotein (LDL). This family of trans-membrane receptors which are highly varied in structure are involved in receptor-mediated endocytosis, phagocytosis of apoptotic cells and bacteria, as well as in cell adhesion [Peiser L. et al., Curr. Opin. Immun. 14(1):123-128, 2002]. Since the massive receptor-mediated uptake of cholesterol from modified LDL can convert cultured macrophages into cholesteryl ester-filled foam cells, similar to those found in atherosclerotic plaques, it has been postulated that these receptors also function in deposition of LDL cholesterol of macrophages in artery walls during the initial stages of atherosclerotic plaque formation [1].
Scavenger receptors (SRs) are termed as such since they mediate the binding of remarkably wide variety of polyanionic ligands [e.g., modified proteins, sulfated polysaccharides and certain polynucleotides [1, 3, 4]. This property led to the hypothesis that these receptors form a part of an in innate immune response by serving as pattern recognition receptors that bind a wide variety of pathogen components [2-5].
SR-B1 (also referred to as SR-BI or CLA-I) is a macrophage scavenger molecule and a receptor for high-density lipoprotein (HDL) [2, 3, 6, 7] that mediates cholesterol uptake from cells [Rigotti A. et al., Curr. Opin. Lipidol., 8:181-8, 1997; Rigotti A. et al., Proc. Natl. Acad. Sci., 94:12610-5, 1997]. SR-B1 can also serve as a receptor for non-HDL lipoproteins and appears to play an important role in reverse cholesterol transport. In vivo experiments showed that this receptor is important for HDL metabolism in mice, and for the metabolism of LDL and HDL cholesterol in humans [Stang H. et al., J. Biol. Chem. 274:32692-8, 1999; Swarnakar S. et al., J. Biol. Chem. 274:29733-9, 1999]. Studies involving the manipulation of SR-B1 gene expression in mice, indicate that its expression protects against atherosclerosis [Kozarsky K. F., and Krieger M., Curr. Opin. Lipidol. 10:491-7, 1999; Ueda Y. et al., J. Biol. Chem. 275:20368-73, 2000; Acton S. L. et al., Mol. Med. Today 5:518-24, 1999]. It was also suggested that HDL and particularly its protein fraction Apo-A1 affect the in vitro production of pro-inflammatory mediators by macrophages (8). Among mediators derived from macrophages that propagate inflammation are interleukin 12 (IL-12), TNF-α and possibly IL-6 whereas, TGF-β and IL-10 have predominantly anti-inflammatory effects [Kiefer R. et al., Prog. Neurobiol. 64(2):109-27, 2001].
PCT Publication No. WO 2004/041179 teaches targeting of scavenger receptor SR-B1 (Cla-I) for the treatment of infectious diseases associated with invasion of foreign antigens such as bacterial or viral antigens (e.g., infection, sepsis and associated inflammation). This is based on the discovery that peptides with an amphipathic helical motif block cellular uptake of LPS (lipopolysaccharide) and proinflammatory responses induced by LPS, LTA (lipoteichoic acid) and bacterial cpn60 (Chaperonin 60) and amyloid peptides in vitro. Thus the inventors of PCT Publication No. WO 2004/041179 conclude that agents with an amphipathic motif targeting SR-BI (scavenger receptor class B type I) could potentially be used to treat sepsis, bacterial and viral infections and inflammatory diseases where LPS, LTA, viral envelope proteins, and/or heat shock proteins contribute to pathogenesis.
WO 2004/041179 does not suggest the above-described agents for the favourable treatment of autoimmune diseases (which are not associated with foreign pathogenic agents such as LPS, nor with amyloid) such as IBD. Nor does the art teach the use of SR-B1 specific antibody sequences having an anti-inflammatory activity activity for the treatment of inflammatory diseases in general and autoimmune diseases in particular, such as multiple sclerosis.
There is thus, a widely recognized need for and it would be highly advantageous to have novel agents and methods using same for targeting SR-B1 and treating autoimmune diseases.